UEFI on motherboard with MBR on HDD: Can I upgrade from Windows 7 to 10?

[Samizdat]

UEFI on motherboard with MBR on HDD: Can I upgrade from Windows 7 to 10?

My motherboard is a Gigabyte GA-Z68X-UD3H-B3 Rev 1.0. It was running BIOS version F12. My boot drive (Disk 0) was a 120MB SSD with a MBR partition table. (I have a second 3TB data drive, Disk 1, that is GPT.) Running Windows 7 Pro, and want to upgrade in place to Windows 10.

I was having trouble with the SSD boot drive (developing bad sectors and running out of room) so I decided to replace it with a 3TB HDD (yes, SSD to HDD.) I used Clonezilla to copy an image of the old drive to the new. It copied over fine. Then in Windows I tried to resize the C: drive on the new HDD to use the entire disk, but I ran into the 2TB size limitation because it is MBR. I extended the partition as much as possible, leaving me with the following on my boot drive:

100 MB System Reserved
2047.90 GB C:
746.52 GB Unallocated Space

I upgraded the BIOS from F12 to UL1 (moving from BIOS to UEFI) thinking (incorrectly) that I would then be able to extend my C: drive to fill the disk. The upgrade went fine but of course my boot drive is still MBR. I hadn't realized I would also need to convert it to GPT to use all 3TB. I do not want to wipe the disk clean if I can avoid it.

Ultimately I want to upgrade to Windows 10. The "Get Windows 10" tool tells me the computer is "good to go" but I am worried about the fact that I'm running UEFI with an MBR boot drive. I don't plan to do a fresh install of Windows 10; I want to download the upgrade and do it in place.

So now I'm a little confused:

- Can I upgrade from Windows 7 to 10 as things are now, with UEFI on the mobo and MBR on the boot drive? From what I've read this might be a problem.
- If so, do I need to enable legacy BIOS support on the mobo? How do I do that? I don't see an obvious option.
- Would I need to enable legacy BIOS support only when I run the Windows upgrade, or would I leave it enabled permanently?
- If I leave it enabled, do I lose out on the benefits of UEFI?
- In any case, if I leave the boot drive as MBR I can't use the unallocated space, right?
- Am I better off flashing the mobo back to the F12 version of the BIOS? Is that even possible?
- Or am I better off using a third party tool to convert my boot drive from MBR to GPT without data loss? If so, what should I use? Do I convert in place, or make an image, wipe and covert the boot disk to GPT, and then copy the image back?

I need to understand things a little more clearly before I can decide what my best option is.

Thanks!

[dmdilks]

First of all if you install windows 7 before you did the bios upgrade it really isn't going to work in UEFI. The other thing is yes you now a UEFI bios but is it really a true UEFI bios. The UEFI upgrade was a after thought from them.

The only way you are going too run in a true UEFI boot. You have to start over again and not with a Reg hard drive too you really need a SSD for it to work right sorry. Yes you can try it but if it was me it really a waste of time running a hard drive in AHCI & UEFI.

Plus working around in the bios is going to be hard they never made a book on it. You are working in the dark and till somebody that really has done this on the the Z68 boards. You will have to do a lot of reseach on the internet.